A Justice Department rule change in March gives more experienced prosecutors oversight over national security cases, but that may not be enough to fix the harm done to scientists who have recently been involved and hurt by false allegations, according to Christopher Kang, the national director for the National Council of Asian Pacific Americans.

Sherry Chen (L), a US federal government worker, and Xiaoxing Xi, chair of the Physics Department at Temple University, speak about the dropped charges against them of spying for China, during a press conference in Washington, DC, September 15, 2015. Prosecutors dropped charges of spying for China against Xi last week and against Chen earlier this year.Saul Loeb/AFP/Getty Images

"Although the Department of Justice did not directly tie these new rules to any particular case, the inference is clear,” Kang told NBC News. “If, as it appears, the Department recognizes that mistakes were made when it brought espionage-related charges against Asian American scientists and then dropped those charges without explanation, then these men and women deserve an explanation now for how their cases were mishandled. The damage to their lives and careers may be irreversible, but a public apology to them and their employers would be an important first step."

A Justice Department memo concerning the rule changes was not released publicly, but a government official provided a copy to the New York Times. Issued by Deputy Attorney General Sally Q. Yates to federal prosecutors nationwide, the memo reportedly requires that national security cases now be overseen by the top national security prosecutors in Washington.

"The new Department of Justice rules to provide greater oversight in all national security related cases are an important step in the right direction,” Kang said. “But the Department should have publicly announced these changes so that the American people could have greater confidence that no prosecution in such cases is based on profiling on race, ethnicity, or national origin.”

Temple University physicist Xiaoxing Xi and Sherry Chen, a hydrologist working with the National Weather Service, were both accused in separate instances of obtaining and sharing sensitive information with China. Chen was accused in October 2014, and the charges against her were dropped in March 2015. The charges against Xi, who pleaded not guilty in June last year, were dropped in September.

“Providing further more uniform Justice Department oversight and support for these types of cases should improve the selection and handling of these cases,” Nelson Dong, a former federal prosecutor and now a national security legal expert based with Dorsey and Whitney in Seattle, told NBC News. “More importantly, that will hopefully reduce the likelihood of misjudgments that could otherwise cause such profoundly damaging effects on innocent people.”